1. Field of the Invention
The present invention relates to a light-emitting device. The present invention also relates to a method for manufacturing the light-emitting device.
In this specification, a semiconductor device means all types of devices that can function by utilizing semiconductor characteristics, and an electro-optical device, a light-emitting device, a display device, a semiconductor circuit, and an electronic appliance are all semiconductor devices.
2. Description of the Related Art
In recent years, research and development have been extensively conducted on light-emitting elements utilizing electroluminescence (EL). In a basic structure of such a light-emitting element, a layer containing a light-emitting substance is interposed between a pair of electrodes. By applying voltage to the element, light emission from the light-emitting substance can be obtained.
The above light-emitting element is a self-luminous element; thus, a light-emitting device including the light-emitting element has advantages such as high visibility, no necessity of a backlight, and low power consumption. In addition, the light-emitting device has advantages in that it can be manufactured to be thin and lightweight and has fast response speed.
Since a light-emitting device including the above light-emitting element can be flexible, use of the light-emitting device for a flexible substrate has been proposed.
As a method for manufacturing a light-emitting device using a flexible substrate, a technique has been developed in which a semiconductor element such as a thin film transistor is manufactured over a substrate such as a glass substrate or a quartz substrate, for example, a space between the semiconductor element and another substrate is filled with an organic resin, and then the semiconductor element is transferred from the glass substrate or the quartz substrate to the other substrate (e.g., a flexible substrate) (Patent Document 1).
In some cases, over a light-emitting element that has been formed over a flexible substrate, another flexible substrate is provided in order to protect a surface of the light-emitting element or prevent entry of moisture or impurities from the outside.
Patent Document 2 and Patent Document 3 each disclose technological thought in which a groove is formed in a flexible substrate and part of the flexible substrate is removed along the groove in order to expose a terminal electrode to which an external signal is input.